Energy absorbing fabric



United States Patent [72] Inventor Homer Lee Ballard South Hill, Virginia [21] Appl. No. 672,029

[22] Filed Oct. 2, 1967 [45] Patented Sept. 29, 1970 [73] Assignee Burlington Industries, Inc.

Greensboro, North Carolina a corporation of Delaware [54] ENERGY ABSORBING FABRIC 8 Claims, 9 Drawing Figs.

[52] US. Cl 139/383, 139/415,139/426 [51] Int. Cl D03d 23/00, D03d 1 1/00 [50] Field ofSearch 139/383,

[56] References Cited UNITED STATES PATENTS 1,582,415 4/1926 Manley 139/415 2,471,166 5/1949 139/383 2,788,023 4/1957 139/410 2,794,450 6/1957 139/411 OTHER REFERENCES 1,180,689, October 1964, Ger. Pub1., Hemesath 139-420. Federal Specification-Belt: Seat Passenger Type, Automotive, Jan 1960 (amendment July 1, 1966),J.IB-185a.

Primary Examiner-James Kee Chi Anorney- Cushman. Darby and Cushman ABSTRACT: A woven fabric capable of energy absorption and having a primary function of absorbing a shock load impulse of an object and/or body to prevent destruction of the same. The fabric is constructed by weaving the same with yarns having relatively different physical properties, the yarns being woven at relatively different tensions so that the resultant fabric is capable of elongation in the order of 10 percent at loads of 500 pounds with full recovery.

Patented Sept. 29, 1970 3,530,904

IN VEN TOR. J g WE/f [5554441950 ENERGY ABSORBING FABRIC The present invention relates to improvements in woven fabrics and, more specifically to those woven fabrics which have energy absorbing characteristics and thus may be used as webbing in safety shoulder harnesses, safety seat belts or the like which enable the same to receive any given impulse and stop the motion of the object giving the impulse in a given space of time and distance without damaging the object by reverberation or backlash.

Heretofore fabric used for webbing of safety shoulder harnesses and/or safety seat belts has been made which will absorb energy from a shock of an accident, thus avoiding serious injury to the wearer. Tests have proved that the human body is quite capable of taking as much as 27 times its own weight with only a seat belt and not incur internal injury. In fact, the U.S. Air Force has conducted tests in which a person rode in a rocket sled to a speed of 632 m.p.h. and stopped in less than 1% seconds without serious injury. Such stoppage is the equivalent of an automobile striking a barrier at 60 mph While the fabric heretofore used in the manufacture of seat belts and harnesses has been satisfactory for use in aircraft and/or automobiles where a serious accident occurs, they are not fully satisfactory in the intended use in accidents which are minor. The belts heretofore used would satisfactorily absorb the shock and would have the proper elongation to provide for such energy absorption but under conditions where there was a minor accident and the force applied to the belt was no more than 500 pounds, the belt had to be replaced as there was a hysteresis in the material rather than full recovery of the material after elongation.

An important object of the present invention is to provide a woven fabric capable of full recovery after a percent elongation at 500 pounds, thus permitting the fabric to be used as safety belting or harness and not necessarily replaceable after a minor accident.

Ancillary to the immediately preceding object, it is a further object of the present invention to provide a fabric having a minimum break strength of 4,000 pounds and an elongation of 40 percent at a 1,500 pound load with 40 percent recovery.

Still another object of the present invention is to provide an energy absorbing fabric capable of absorbing energy at least in one of a warpwise or fillingwise direction.

Still another object of the present invention is to provide an improved energy absorbing fabric capable of absorbing energy in a warpwise direction, the warpwise yarns having some of the same which are medium break strength high elongation yarns woven under high tension and other of the warp yarns being high break strength yarns with low elongation, the same being woven under low tension, thus resulting in a high crimp or weave takeup in the same.

Ancillary to the immediately preceding object it is a further object of the present invention to provide an energy absorbing fabric in which the high elongation yarns accept the load and carry the same until practically all of the crimp is pulled out of the high strength low elongation yarns at which time such low elongation yarns begin to share the load and elongate along with the high elongation yarns.

A still further object of the present invention is to provide an improved energy absorbing fabric structure in which the same is woven with filling yarns having different physical properties, at least some of the filling yarns being crimped high break strength low elongation yarns whereas other of the filling yarns are high elongation medium break strength yarns capable of taking elongation in a fillingwise direction until the crimp is pulled out of the high strength low elongation yarns at which time there is a sharing of the load by the yarns of different physical characteristics as the yarns elongate.

These and other objects and advantages of the present invention will appear more fully in the following specification, claims and drawings in which:

FIG. 1 is a diagrammatic fragmentary longitudinal sectional view ofan energy absorbing fabric;

FIG. 2 is a pegging plan for weaving the fabric shown in FIG. 1;

FIG. 3 is an enlarged perspective view of a fragmentary portion of a piece of fabric or webbing when woven as shown in FIG. 1;

FIG. 4 is a diagrammatic fragmentary longitudinal sectional view similar to FIG. 1 but showing a modified form of weave capable of employing the present invention;

FIG. 5 is a harness pegging plan similar to FIG. 2 but showing the plan for the weave of FIG. 4;

FIG. 6 is an enlarged perspective view of a fragmentary portion of a piece of fabric woven according to the weave of FIG.

FIG. 7 is a view similar to FIGS. 1 and 4 but showing a still further modified weave;

FIG. 8 is a harness pegging diagram for producing the fabric of FIG. 7, and

FIG. 9 is an enlarged perspective view of a fragmentary portion of the fabric woven as shown in FIG. 7.

As mentioned at the outset of the specification, the present invention relates to an improved fabric having as its primary function that of absorbing a shock load impulse of an object and/or body and to prevent the destruction and/or injury resulting therefrom. Various weaves and fabric constructions are well known to the art of textile manufacturing for producing fabrics which will absorb limited shock load impulse. The present invention differs from such prior constructions in that the fabric is constructed with a particular selection of yarns having certain differentphysical properties the yarn being arranged during weaving so that the fabric is capable of receiving any given impulse and stop the motion in a given space of time and distance without damaging reverberation or backlash. A prime feature of the present invention is to so select the yarns having particular different physical properties and so arrange those yarns that the fabric, when used as webbing in a safety harness or belt, will have full recovery after being subjected to an elongation of 10 percent caused by a load in the order of 500 pounds. Of course, the fabric construction of the present invention contemplates utilizing the various interlaces of one yarn with another to allow the crimp in some of the yarns along with normal elongation in the other of the yarns to stretch out and regain slowly so as to avoid violent recoil.

To obtain the desired results mentioned above, the fabric construction consists of using two yarns of varying physical properties in either a warpwise direction or a fillingwise direction or in both directions if so desired. One yarn of the two yarns has high breaking strength and low elongation at break of 14 percent to 24 percent. The other yarn of the two yarns is a medium break strength yarn with up to 60 percent elongation at break. It has been found that an excellent yarn having high breaking strength but low elongation is a high tenacity nylon yarn whereas an excellent yarn of medium break strength but high elongation has been found to be spun nylon. Of course, textured filament yarns may be used as medium strength high elongation yarns.

Assuming that it is desired to have the fabric so constructed as to be energy absorbing in a warpwise direction, the fabric is woven with the warp ends made up of the two yarns having different physical properties. In this case, the warp ends which are made up of high strength low elongation yarns are woven under a relatively-low tension while the warp ends made from the medium strength high elongation yarns are woven under relatively high tension so as to cause these warp ends to lay in almost a straight line thereby causing the other warp ends, i.e.,

' the high strength low elongation, to be woven with a rather high crimp or weave takeup. The interlaces of the yarn in the fabric construction is such that the high elongation yarns take the greatest part of the shock load up to a given point before the low elongation yarns are pulled to the point of elongating the crimp of the interlaces at which point the low elongation yarn then begins to share the load and elongate up to full load along with the high elongation yarns.

A webbing fabric woven as described above will have a minimum break strength of 4,000 pounds and an elongation of percent at about a 500 pound load with a full recovery. There will be about a 40 percent elongation of such a fabric at a 1,500 pound load, the fabric then having a 40 percent recovery.

Referring now to the drawings and particularly to FIGS. 1, 2 and 3, there is disclosed a fabric construction for webbing for use in safety harnesses or belts of the present invention. In FIG. 1 the warp ends 1W and 2W are the high strength yarns having an ultimate elongation of only 14 percent to 24 percent. These yarns are woven under a relatively low tension with the odd numbered warp ends weaving two up and two down pattern and the even numbered warp ends weaving two down and two up pattern as shown in the harness pegging plan of FIG. 2. With respect to FIG. 2, the numbers to the left and outside of the squares represent the picks of filling from 1 to 4 respectively. The numbers appearing within the squares represent the warp harness which also corresponds with the warp yarn designation. Squares with numbers indicate the harnesses raised on the particular pick, and conversely the squares that are empty indicate the harnesses lowered on that pick. The warp end 3W represents the medium high strength yarn having an ultimate elongation of 60 percent at break. This yarn is woven under relatively high tension so as to cause the same to lie in a straight line thereby resulting in the other warp yarn 1W and 2W being woven with a rather high crimp or weave takeup. The relative physical properties of the two yarns (1W, 2W) and (3W) along with the relative tensions under which they are woven is such as to cause the high elongation yarns to accept the initial load and carry it until practically all of the crimp is pulled out of the high strength low elongation yarns at which time such low elongation yarns begin to share the load and both yarns elongate together.

A fabric made according to the immediately above description from warp yarns of high tenacity nylon and spun nylon gave the following results:

1. Under a 500 pound load on a 1 /16" webbing, the elongation was 13.6 percent with a 58.8 percent regain in 15 seconds and with a 100 percent regain in 60 seconds.

2. Under a 1,500 pound load there was an elongation of 35 percent with a slow recovery of 74.5 percent in 10 minutes.

3. Under a 2,500 pound load there was an elongation of 50 percent with a total recovery of 59.4 percent in 10 minutes.

4. Total break strength of the webbing was 5,010 pounds.

Referring now to FIGS. 4 through 6 inclusive, the warp ends 1W to 4W are high strength low elongation yarns having an ultimate elongation of 14 percent to 24 percent, the same being woven under relatively low tension with the odd numbered ends weaving in a three up, one down alternating order and with the even numbered ends weaving in a three down, one up alternating order such as shown in the pegging plan FIG. 5. The warp end 5W represents the medium high strength yarn with an ultimate elongation of 60 percent and, of course, this yarn is woven under relatively high tension such as to cause the yarn to lay in almost a straight line, thus resulting in the warp yarns 1W to 4W being woven with a rather high crimp and weave takeup. This arrangement of fabric weave, just as the arrangement described with respect to FIGS. 1 through 3, produces the same results.

A further fabric weave is disclosed in FIGS. 7 through 9 inclusive and it will be noted that in this weave the warp yarns are designated 1W through 5W respectively. Warp ends 1W to 4W represent the medium strength yarns having high elongation and woven under relatively high tension in a 3 x l weave with the warp ends 1W and 3W producing a l x 1 face and the warp ends 2W and 4W producing a 1 x 1 back as indicated. Warp ends SW and 6W represent the high strength low elongation yarns with ultimate elongation of 14 to 24 percent which are woven under low tension. The warp ends SW and 6W weave in a 2 x 2 face through both the face and back of the fabric but to not only bind the face and back of the fabric but to produce considerable crimp on weave takeup. Consequently, the thicker the fabric the greater will be the weave takeup and crimp. Also the relative tensions at which the yarn is woven and the relative physical properties of the yarns again provide the desired results of the present invention.

While the energy absorbing characteristic has been described with respect to producing the same in a longitudinal direction of the webbing or in a warpwise direction, it will be fully understood that by utilizing filling threads having different physical properties, the webbing can be made to absorb energy in a fillingwise direction. When utilizing yarns of different physical properties in a fillingwise direction, it would be desirable to use the high strength low elongation yarn with a crimp already provided in the same.

It will be noted that at the outset of the specification it was mentioned that high tenacity nylon was utilized for the high strength low elongation yarns whereas a spun nylon was used for the medium strength high elongation yarns. A percent undrawn nylon could not be used as it would result in a heavy, bulky fabric and thus present weaving problems. Another reason for not using 100 percent undrawn nylon is that after it reaches its elastic limit, the rate of elongation is uniform until near the limit of elongation and thus there is no gradual deceleration when used as a safety harness.

The foregoing description of the energy absorbing fabrics fully and effectively accompanies the objects and advantages of the present invention; however, certain modifications may be made, for example to the weaving pattern, without departing from the spirit of the invention.

Therefore, the terminology used throughout the specification is for the purpose of description and not limitation, the scope of the invention being defined in the claims.

I claim:

1. A woven fabric capable of energy absorption in at least one direction, said woven fabric having warp yarns interwoven with filling yarns, the fabric being characterized by having some of the yarns extending in the direction capable of energy absorption being high break strength low elongation yarns capable of an ultimate elongation to break of 14 percent to 24 percent while other yarns extending in the direction capable of energy absorption being medium break strength high elongation yarns capable of an elongation to break of 60 percent so that the fabric is capable of an elongation of 10 percent at 500 pounds load with full recovery and capable of an elongation of 40 percent at a 1,500 pound load with 40 percent recovery.

2. A woven fabric as claimed in claim 1 in which said fabric is capable of energy absorption in the warpwise direction.

3. A woven fabric as claimed in claim 1 in which the high strength low elongation yarns capable of ultimate elongation to break of 14 percent to 24 percent are made from high tenacity nylon and in which the medium break strength yarns are made from spun nylon.

4. A woven fabric as claimed in claim I in which said high strength low elongation yarns are woven into the fabric under relatively low tension and in which said medium strength high elongation yarns are woven into the fabric under relatively high tension.

5. A woven fabric as claimed in claim 1 in which the fabric is capable of energy absorption in the warpwise direction and in which said high strength low elongation yarns are woven into the fabric under relatively low tension and in which said medium strength and high elongation yarns are woven into the fabric under relatively high tension whereby the weave takeup and crimp of the high strength low elongation yarn is high.

6. A woven fabric as claimed in claim 1 in which said fabric is capable of energy absorption in the fillingwise direction.

7. A woven fabric as claimed in claim 6 in which some of the yarns extending in the fillingwise direction are high break strength low elongation yarns which are crimped and in which other of the filling yarns are medium strength high elongation yarns.

8. A woven fabric as claimed in claim 1 in which said fabric is capable of energy absorption in both warpwise and filling directions. 

